Sensor Applique With Ultra Violet Curable Pressure Sensitive Adhesive

ABSTRACT

An applique for covering a clear substrate through which light is at least one of transmitted and received includes: a transparent sheet having: a first surface; and a second surface that is opposite the first surface; and a ultraviolet (UV) curable pressure sensitive adhesive that is disposed on the first surface of the transparent sheet, that is curable using UV light, and that is configured to adhere the transparent sheet to a third surface of the clear substrate.

INTRODUCTION

The information provided in this section is for the purpose of generallypresenting the context of the disclosure. Work of the presently namedinventors, to the extent it is described in this section, as well asaspects of the description that may not otherwise qualify as prior artat the time of filing, are neither expressly nor impliedly admitted asprior art against the present disclosure.

The present disclosure relates to sensors with lenses or windows andmore particularly to appliques for covering lenses of sensors.

Light emitting and/or receiving sensors may be exposed to harshenvironmental conditions. For example, a vehicle may include one or morelight emitting and receiving sensors, such as, cameras, light detectionand ranging (LIDAR) sensors, rangefinders, and other types of sensors.The light emitting and receiving sensors are positioned on the exteriorof the vehicle and exposed to the environment.

Light emitting and/or receiving sensors include a lens and/or a windowthrough which light rays are transmitted and received. The exteriorsurface of the lens or window may be coated to protect the lens fromscratches. The exterior surface of the lens or window may be cleaned,for example, via air or washer fluid, to remove dirt and debris. Thepresence of dirt and/or debris on the exterior surface of the lens orwindow may decrease light transmission through the lens or window andmay decrease performance of the sensor.

SUMMARY

In a feature, an applique for covering a clear substrate through whichlight is at least one of transmitted and received includes: atransparent sheet having: a first surface; and a second surface that isopposite the first surface; and a ultraviolet (UV) curable pressuresensitive adhesive that is disposed on the first surface of thetransparent sheet, that is curable using UV light, and that isconfigured to adhere the transparent sheet to a third surface of theclear substrate.

In further features, the UV curable pressure sensitive adhesive includesadhesive 8148 by 3M corporation.

In further features, a thickness of the UV curable pressure sensitiveadhesive is 2 mils.

In further features, the transparent sheet is a fluoropolymer sheet.

In further features, the transparent sheet is fluorinated ethylenepropylene.

In further features, the UV curable pressure sensitive adhesive is a dryadhesive.

In further features, the UV curable pressure sensitive adhesive includesa sheet of UV curable adhesive that is cured using the UV light afterapplication of the applique to the clear substrate.

In further features, prior to application of the UV curable pressuresensitive adhesive to the transparent sheet, the first surface of thetransparent sheet is treated by at least one of an ozone treatmentprocess, a corona treating process, a chemical etching process, and aplasma treating process.

In further features, the UV curable pressure sensitive adhesive isconfigured to adhere better to the first surface of the transparentsheet than to the third surface of the clear substrate.

In further features: the clear substrate exhibits a first index ofrefraction; the UV curable pressure sensitive adhesive exhibits a secondindex of refraction after being UV cured; the transparent sheet exhibitsa third index of refraction; with the third index of refraction of thetransparent sheet is less than the second index of refraction; and thesecond index of refraction is less than the first index of refraction ofthe clear substrate.

In further features, the third surface of the clear substrate is aplanar surface.

In further features, the third surface of the clear substrate is aconvex surface.

In further features, a release liner covers the UV curable pressuresensitive adhesive.

In further features, the UV curable pressure sensitive adhesive isconfigured to adhere better to the first surface of the transparentsheet than to the release liner.

In further features, a coating on the second surface of the transparentsheet.

In further features, the coating includes at least one of: an anti-icingcoating; an anti fouling coating; an anti-scratch coating; ananti-reflective coating; a tint; a reflective coating; and a hydrophiliccoating.

In a feature, a sensor includes: a clear substrate having a firstsurface; a sensor module configured to receive light through the clearsubstrate; and an applique that is adhered to the first surface of theclear substrate and that includes: a transparent sheet having: a secondsurface; and a third surface that is opposite the second surface; and aultraviolet (UV) cured pressure sensitive adhesive that is sandwichedbetween the second surface of the transparent sheet and the firstsurface of the clear substrate and that adheres the transparent sheet tothe clear substrate.

In further features, the sensor module is further configured to transmitlight through the clear substrate.

In further features: the transparent sheet is fluorinated ethylenepropylene; and the UV cured pressure sensitive adhesive is adhesive 8148by 3M corporation that is cured using UV light.

In further features, the applique further includes, on the third surfaceof the transparent sheet, at least one of: an anti-icing coating; ananti fouling coating; an anti-scratch coating; an anti-reflectivecoating; a tint; a reflective coating; and a hydrophilic coating.

Further areas of applicability of the present disclosure will becomeapparent from the detailed description, the claims and the drawings. Thedetailed description and specific examples are intended for purposes ofillustration only and are not intended to limit the scope of thedisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a schematic partially exploded cross sectional view of asensor;

FIG. 2 is a schematic cross sectional view of the sensor, showing anapplique positioned over a lens of the sensor;

FIG. 3 is a schematic perspective view of the applique showing a releaseliner partially removed;

FIG. 4 includes a method of applying the applique to the lens of thesensor and curing an ultra violet (UV) curable pressure sensitiveadhesive of the applique; and

FIG. 5 includes a schematic partially exploded cross sectional view of asensor with an applique including a coating.

In the drawings, reference numbers may be reused to identify similarand/or identical elements.

DETAILED DESCRIPTION

Sensors, such as light detection and ranging (LIDAR) sensors transmitand receive light through a clear substrate, such as a polycarbonatelens. Sensors can be exposed to harsh environmental conditions, such asthe environment around a vehicle.

According to the present disclosure, an anti-fouling applique is appliedto the clear substrate of a sensor, such as a LIDAR sensor. Theanti-fouling applique includes a pressure sensitive adhesive and atransparent sheet. The pressure sensitive adhesive adheres thetransparent sheet to the clear substrate of the sensor. The pressuresensitive adhesive is cured via ultraviolet light after the applique isapplied to the clear substrate of the sensor. As an example, thepressure sensitive adhesive may include UV curable adhesive 8148 by 3Mor another suitable UV curable adhesive. A UV cured adhesive may providebetter light transmission characteristics over time than non-UV curedadhesives, such as non-UV curable acrylic based adhesives. A UV curedadhesive may also perform better than non-UV cured adhesives afterexposure to methanol, which is an ingredient in washer fluid. Invehicles, washer fluid may be used to clean the transparent sheet duringuse. As used herein, UV light may include light having wavelengthbetween 200 and 405 nanometers (nm), inclusive. This includes near UV(NUV) light within the wavelength range of, for example, 385-405 nm. Forexample only, the UV light used to cure the UV curable pressuresensitive adhesive may have a wavelength of 365 nm or be NUV lightwithin 385-405 nm wavelength range.

FIG. 1 includes a partially exploded cross sectional view of a sensor 20and an applique 30. FIG. 2 includes cross sectional view of the sensor20 after application of the applique 30.

Referring now to FIGS. 1 and 2, the sensor 20 includes a sensor module22 that is operable to transmit and/or receive light rays 24 (shown inFIG. 2). The sensor module 22 may be configured, for example, as a rangefinder, a LIDAR sensor 20, a camera, or another type of sensing device.The sensor module 22 generates output signals based on the receivedlight.

The sensor 20 further includes a clear substrate 26, which is attachedto the sensor module 22. As noted above, the sensor module 22 emitsand/or receives light rays 24. The light rays 24 pass through the clearsubstrate 26. The clear substrate 26 may be referred to as a lens, awindow, a pane, or a panel. The clear substrate 26 may be configured toconcentrate and disperse the light rays 24 as the light rays 24 passthrough the clear substrate 26.

The clear substrate 26 includes a first surface 28. The first surface 28of the clear substrate 26 may be considered an exterior or outer surfaceof the clear substrate 26. In the examples of FIGS. 1 and 2 anddescribed herein, the first surface 28 of the clear substrate 26 is anonplanar surface. For example, the first surface 28 of the clearsubstrate 26 may include a concave surface or a convex surface, such asshown. However, the first surface 28 of the clear substrate 26 mayinclude a planar surface. The non-planar shape of the first surface 28of the clear substrate 26 controls the concentration and dispersion oflight rays 24 passing through the clear substrate 26.

The clear substrate 26 is made of a transparent material. The clearsubstrate 26 may include and be manufactured from, but is not limitedto, one of a glass material or a plastic material. For example, theclear substrate 26 may include and be manufactured from silica,borosilicate glass, quartz, polycarbonate (e.g., Trivex by PPG™), CR-39plastic, crown glass, or another suitable transparent material.

The sensor 20 includes the applique 30, which is adhered to the firstsurface 28 of the clear substrate 26. FIG. 1 shows the applique 30 priorto the applique 30 being adhered to the clear substrate 26. FIG. 2 showsthe applique 30 adhered to the clear substrate 26.

Referring to FIGS. 1 and 2, the applique 30 includes a transparent sheet32, and an ultra violet (UV) curable pressure sensitive adhesive 34. Theterm “sheet” may refer to a thin piece of a solid material formed into aself-supporting layer. The term “sheet” does not include a layer or filmformed from a dried liquid. The applique 30 is adhered to first surface28 of the clear substrate 26 of the sensor 20 via the pressure sensitiveadhesive 34. The applique 30 may be adhered to other types of clearsubstrates, such as clear substrates of window panels for example.

The transparent sheet 32 includes a first surface 36 and an opposingsecond surface 38. The first surface 36 of the transparent sheet 32faces the first surface 28 of the clear substrate 26. The second surface38 of the transparent sheet 32 is opposite the first surface 36, facesoutward, and is exposed to the environment.

As shown in FIG. 1, the transparent sheet 32 includes a thickness 40.The thickness 40 of the transparent sheet 32 may be between 10 and 200microns. In other examples, the thickness 40 of the transparent sheet 32may be less than 10 microns or greater than 200 microns.

The transparent sheet 32 may be made of a fluoropolymer. For example,the transparent sheet 32 may be a fluorinated ethylene propylene (FEP)sheet. As other examples, the transparent sheet 32 may be another typeof material, such as another fluoropolymer, such as but not limited toEthylene tetrafluoroethylene (EFTE), Perfluoroalkoxy alkane (PFA),amorphous fluoroplastics (AF), or an alternating copolymer of ethyleneand ETFE.

The first surface 36 of the transparent sheet 32 is treated to improveadhesion. More specifically, the first surface 36 of the transparentsheet 32 may be subjected to one or more processes to clean and preparethe first surface 36 to increase surface adhesion. For example, thefirst surface 36 of the transparent sheet 32 may be treated to improveadhesion using one of an ozone treating process, a corona treatingprocess, a chemical etching process, or a plasma treating process. Bytreating the first surface 36 of the transparent sheet 32 for adhesion,the pressure sensitive adhesive 34 adheres better to the first surfaceof the transparent sheet 32 than the first surface 28 of the clearsubstrate 26 both before and after UV curing. Thus, the applique 30including both the pressure sensitive adhesive 34 and the transparentsheet 32 can be removed without damaging the first surface 28 of theclear substrate 26 and without the pressure sensitive adhesive 34remaining on the first surface 28. For example, the applique 30 can beremoved and replaced with another one of the appliques 30.

The pressure sensitive adhesive 34 is disposed on the first surface 36of the transparent sheet 32 after the first surface 36 of thetransparent sheet 32 has been treated to improve adhesion. The pressuresensitive adhesive 34 is applied to the first surface 36 of thetransparent sheet 32 before being cured (i.e., in not yet UV cured formas a not yet UV cured pressure sensitive adhesive). The pressuresensitive adhesive 34 may be applied to the first surface 36 of thetransparent sheet 32, for example, by spraying, doctor blade, rolling,or pressed or in another suitable manner. In various implementations,the pressure sensitive adhesive 34 is provided as a sheet that can becured to a hardened form via exposure to UV light. The pressuresensitive adhesive 34 is exposed to and cured via UV light to form theUV cured pressure sensitive adhesive 34 on the first surface 36 of thetransparent sheet 32.

The pressure sensitive adhesive 34 adheres the transparent sheet 32 tothe first surface 28 of the clear substrate 26. The pressure sensitiveadhesive 34 includes a distinct category of adhesive materials that in adry form (e.g., substantially free of both water and solvent) ispermanently tacky (after UV curing) at environmental temperatures (e.g.,−50 degrees F. to 180 degrees F.) and firmly adheres to a variety ofdifferent types of surfaces at environmental temperatures upon contactwithout the need of more than 20 pounds per square inch of pressurebeing applied and is curable via UV light. The pressure sensitiveadhesive 34 may include a linear or branched, random or blocked,polymer, having one, two, three, or more monomer units. The pressuresensitive adhesive 34 may be a UV curable acrylic adhesive. Examples thepressure sensitive adhesive 34 include OCA 8148-X UV curable adhesivesheet by 3M™ (where X is the thickness, such as 2 mils), 723 UV curableadhesive gel by Dynamax, 723 UV curable adhesive gel by Dynamax and anacrylic PSA binder polymer, U3334 UV adhesive by Cyberbond, 3335 UVcurable adhesive by Cyberbond, 73 UV curable adhesive by Norland, 146HUV curable adhesive by Norland, SPF 137 UV curable adhesive by Rahn, SPF137 UV curable adhesive by Rahn with an acrylic filler (e.g., LA2140e byKurarity, SPF 255 UV curable adhesive by Rahn, SPF 307 UV curableadhesive by Rahn, UV-5804E UV curable adhesive by EpoxySet, and UVcurable adhesive mod 137 by Chemsultants. pressure sensitive adhesive 34does not form a chemical bond with either the transparent sheet 32 orthe clear substrate 26. OCA 8148-X UV curable adhesive sheet by 3M™ maybe an acrylic adhesive that is UV curable polymer that is made fromacrylic acid, methacrylic acid, or a chemically substituted version ofthese compounds. As stated above, however, the pressure sensitiveadhesive 34 adheres better to the first surface 36 of the transparentsheet 32 than the first surface 28 of the clear substrate 26. Examplesof pressure sensitive adhesives 34 can include a material chosen from UVcurable adhesives of acrylic resin, polyurethane, rubber,styrene-butadiene-styrene copolymers, ethylene vinyl acetate, styreneblock copolymers, polyisobutene (PIB) and silicone, and combinationsthereof, such as styrene-ethylene/butylene-styrene (SEBS) blockcopolymer, styrene-ethylene/propylene (SEP) block copolymer,styrene-isoprene-styrene (SIS) block copolymer, or combinations thereof.The pressure sensitive adhesive 34 can include a pendant UV curablemonomer. For example, UV curable acrylic adhesive may include a UVcurable monomer pendant off the main chain.

The pressure sensitive adhesive 34 may be a dry adhesive, such as asheet, or a gel. Once applied to the first surface 36 of the transparentsheet 32 and readied for application onto the first surface 28 of theclear substrate 26, the pressure sensitive adhesive 34 is substantiallyfree of water and solvent. The pressure sensitive adhesive 34 isoptically clear both before and after UV curing. For example, thepressure sensitive adhesive 34 may include optically clear UV curableadhesive 8148 from the 3M™ Corporation.

The clear substrate 26 exhibits an index of refraction. The index ofrefraction of a material is a dimensionless number that describes howlight propagates through that material. The pressure sensitive adhesive34 and the transparent sheet 32 also exhibit a respective index ofrefraction.

The materials of the clear substrate 26, the pressure sensitive adhesive34, and the transparent sheet 32 may be selected such that the index ofrefraction of the transparent sheet 32 is less than the index ofrefraction of the UV cured pressure sensitive adhesive 34. The index ofrefraction of the pressure sensitive adhesive 34 is less than the indexof refraction of the clear substrate 26. By configuring the transparentsheet 32, the pressure sensitive adhesive 34, and the clear substrate 26in this manner, i.e., with the index of refraction of the transparentless than the index of refraction of the UV cured pressure sensitiveadhesive 34, which is less than the index of refraction of the clearsubstrate 26, the transparent sheet 32 and the pressure sensitiveadhesive 34 act as an anti-reflection layer for the clear substrate 26.This improves light transmission through the clear substrate 26.

FIG. 3 includes a schematic perspective view of the applique 30 with arelease liner 42 partially removed. Optionally, if the applique 30 isnot going to be applied to the first surface 28 of the clear substrate26 for a period of time, the release liner 42 may be applied over the UVcurable pressure sensitive adhesive 34. The release liner 42 may protectthe pressure sensitive adhesive 34 from debris and/or dust until theapplique 30 is ready to be applied to the clear substrate 26. Therelease liner 42 may include a sheet of material that is removable fromthe pressure sensitive adhesive 34, and that does not damage or disruptthe pressure sensitive adhesive 34 on the first surface 36 of thetransparent sheet 32. The pressure sensitive adhesive 34 is more adheredto the first surface 36 of the transparent sheet 32 than to the releaseliner 42. The release liner 42 may be omitted, for example, if theapplique 30 is applied to the clear substrate 26 shortly after thepressure sensitive adhesive 34 has been applied to the clear substrate26.

FIG. 4 includes a flowchart depicting an example method of manufacturingthe applique 30 and applying the applique to the sensor 20. At 404, thetransparent sheet 32 is obtained. The first surface 36 of thetransparent sheet 32 is treated to improve adhesion, as described above.For example, the first surface 36 of the transparent sheet 32 may besubjected to an ozone treating process, a corona treating process, achemical etching process, a plasma treating process, and/or one or moreother suitable adhesion improving processes. The first surface 36 of thetransparent sheet 32 is treated for adhesion to improve the adhesionbetween the pressure sensitive adhesive 34 and the transparent sheet 32.

At 408, the (not yet UV cured) UV curable pressure sensitive adhesive 34is applied to the first surface 36 of the transparent sheet 32. Themanner in which the pressure sensitive adhesive 34 is applied to thefirst surface 36 of the transparent sheet 32 may depend upon theproperties of the pressure sensitive adhesive 34. For example, thepressure sensitive adhesive 34 may be applied as a sheet, or may beapplied in a liquid solution, and allowed to dry in order to form a filmof the pressure sensitive adhesive 34.

Optionally, at 416 the release liner 42 may be applied over the UVcurable pressure sensitive adhesive 34 to protect the pressure sensitiveadhesive 34.

Once the applique 30 has been prepared, the applique 30 can be appliedto the first surface 28 of the clear substrate 26. If the applique 30was prepared with the release liner 42, the release liner 42 is peeledoff to expose the pressure sensitive adhesive 34 at 420 prior toapplication of the applique 30 to the first surface 28 of the clearsubstrate 26. The transparent sheet 32 is adhered to the first surface28 of the clear substrate 26, such as shown in FIG. 2, with the pressuresensitive adhesive 34 contacting the first surface 28 of the clearsubstrate 26.

Depending upon the specific characteristics of the UV curable pressuresensitive adhesive 34, a liquid, such as water, may be applied to thefirst surface 28 of the clear substrate 26 prior to the application ofthe applique 30 to the first surface 28 of the clear substrate 26. Theliquid may allow the transparent sheet 32 to be shifted into a properposition and/or allow any air bubbles and wrinkles in the transparentsheet 32 to be worked out from between the clear substrate 26 and thetransparent sheet 32. Once the transparent sheet 32 is properlypositioned on the clear substrate 26, sufficient pressure is applied tothe transparent sheet 32 at 424 to create the adhesion between thepressure sensitive adhesive 34 and the first surface 28 of the clearsubstrate 26.

At 428, the UV curable pressure sensitive adhesive 34 is cured byexposing the UV curable pressure sensitive adhesive 34 to a UV lightsource, such as a light source including one or more UV light bulbs, oneor more UV emitting light emitting diodes (LEDs), or another suitablesource of UV light. The UV light may include light having wavelengthbetween 200 and 405 nanometers (nm), inclusive. This includes near UV(NUV) light within the wavelength range of, for example, 385-405 nm. Forexample only, the UV light used to cure the UV curable pressuresensitive adhesive may have a wavelength of 365 nm or be NUV lightwithin 385-405 nm wavelength range. The exposure of the (not yet cured)UV curable pressure sensitive adhesive 34 cures the UV curable pressuresensitive adhesive 34 and forms the UV cured pressure sensitive adhesive34. Once applied to the clear substrate 26 and UV cured, the transparentsheet 32 may exhibit a peel strength of between 0.5 and 3.0 pounds perinch.

Via the above, the transparent sheet 32 may be easily removed from theclear substrate 26 (e.g., at regular maintenance intervals) and a newone of the appliques 30 can be applied. This may maintain a clear,clean, protective surface over the clear substrate 26. The transparentsheet 32 of the applique 30, e.g., fluorinated ethylene propylene, incombination with the UV cured pressure sensitive adhesive 34, providesgood light transmission through the clear substrate 26, does not degradein response to UV exposure, maintains proper adhesion even when exposedto lens cleaning solvents such as window washer fluid (e.g., includingmethanol), and easily sheds dirt and other debris to keep the clearsubstrate 26 clean and protected.

Testing was conducted on examples described above. Fluorinated ethylenepropylene (FEP) appliques were fabricated with a range of pressuresensitive adhesives (PSA) to provide a removable anti-soiling solutionfor sensors. Optical transparency, peel strength, UV exposure, methanolresistance, camera resolution, and LIDAR attenuation were tested. FEPappliques using UV cured adhesive 8148 from the 3M™ Corporation, opticalgrade, outdoor rated PSA performed suitably for all measurements. Theseappliques improved the light transmission on substrates due to theirlower index of refraction compared to silica and lost 2-6% of light onpolycarbonate lenses. For example, silica may have an n value of 1.5,while the pressure sensitive adhesive may have an n value of 1/47, andthe clear substrate (e.g., FEP) has an n value of 1.34. Appliques of FEPon UV cured adhesive 8148 from the 3M™ Corporation maintained a 2±0.5lb/in peel strength from 20° F. to 120° F. demonstrating they wereremovable but would not fall off from temperature variations. After a 3month equivalent UV exposure, the applique transmission decreased by anegligible 0.5% and there was no change in anti-fouling results. FEP onUV cured adhesive 8148 from the 3M™ Corporation did not de-bond offglass after 7 days soak in methanol or lose transparency, whichindicates that these appliques will not be removed or degraded by sensorfluidic wash systems.

The following Table 1 illustrates performances of different types ofadhesives relative to the clear substrate 26 (Polycarbonate) for 940nanometer (nm) wavelength light (used by LIDAR sensors).

TABLE 1 Applique made Applique made with 5 mil FEP Applique made with 5mil FEP on 3M 8148 with 5 mil FEP Sample Polycar- on mod 137 adhesiveafter on 3M 8172 angle v bonate adhesive UV curing adhesive incidentStrehl RMS Strehl RMS Strehl RMS Strehl RMS light ratio (λ) ratio (λ)ratio (λ) ratio (λ)  0° .96 0.031 .81 0.072 .95 0.034 .76 0.086 10° .970.027 .66 0.120 .96 0.033 .75 0.088 20° .95 0.029 .64 0.125 .96 0.034.73 0.092 30° .95 0.036 .59 0.133 .95 0.034 .67 0.102 45° .83 0.069 .440.157 .95 0.035 .48 0.133

Table 1 compares the Strehl ratios and errors (RMS (γ)) of the clearsubstrate 26 (without the transparent sheet 32 and without adhesive)relative to the inclusion of UV curable adhesive mod 137 byChemsultants, OCA 8148-2 UV curable adhesive sheet by 3M™, and acrylicbased (non-UV curable) 8172 adhesive sheet by 3M™ and the transparentsheet 32. As illustrated by Table 1, OCA 8148-2 UV curable adhesivesheet by 3M™ performed better than UV curable adhesive mod 137 byChemsultants and acrylic based (non-UV curable) 8172 adhesive sheet by3M™ in terms of Strehl Ratio and error. The OCA 8148-2 UV curableadhesive sheet by 3M™ performed closely to the clear substrate 26 aloneand performed better than the clear substrate 26 alone in terms ofStrehl ratio and error at a sample angle versus incident light of 45°.

The following Table 2 illustrates performances of different types ofadhesives relative to the clear substrate 26 (Polycarbonate) for 1550 nmwavelength light (used by LIDAR sensors).

TABLE 2 Applique made Applique made with 5 mil FEP Applique made with 5mil FEP on 3M 8148 with 5 mil FEP Sample Polycar- on mod 137 adhesiveafter on 3M 8172 angle v bonate adhesive curing adhesive incident StrehlRMS Strehl RMS Strehl RMS Strehl RMS light ratio (λ) ratio (λ) ratio (λ)ratio (λ)  0° .96 0.033 .80 0.083 .91 0.051 .80 0.079 10° .94 0.039 .770.090 .94 0.042 .82 0.072 20° .93 0.041 .75 0.092 .92 0.046 .81 0.07730° .91 0.048 .65 0.112 .92 0.047 .71 0.098 45° .78 0.082 .34 0.176 .900.055 .61 0.147

Table 2 compares the Strehl ratios and errors (RMS (γ)) of the clearsubstrate 26 (without the transparent sheet 32 and without adhesive)relative to the inclusion of UV curable adhesive mod 137 byChemsultants, OCA 8148-2 UV curable adhesive sheet by 3M™, and acrylicbased (non-UV curable) 8172 adhesive sheet by 3M™ and the transparentsheet 32. As illustrated by Table 2, OCA 8148-2 UV curable adhesivesheet by 3M™ performed better than UV curable adhesive mod 137 byChemsultants and acrylic based (non-UV curable) 8172 adhesive sheet by3M™ in terms of Strehl Ratio and error. The OCA 8148-2 UV curableadhesive sheet by 3M™ performed closely to the clear substrate 26 aloneand performed better than the clear substrate 26 alone in terms ofStrehl ratio and error at a sample angle versus incident light of 45°.

The following Table 3 illustrates performances of different types ofadhesives with the transparent sheet 32 for 1550 nm wavelength light(used by LIDAR sensors) with 0° incident light before and after mentholexposure.

TABLE 3 Applique made Applique made with 5 mil FEP Applique made with 5mil FEP on 3M 8148 with 5 mil FEP on mod 137 adhesive after on 3M 81720° incident adhesive curing adhesive light, 1550 nm Strehl RMS StrehlRMS Strehl RMS wavelength ratio (λ) ratio (λ) ratio (λ) Before .80 0.083.91 0.051 .80 0.079 methanol exposure After .51 0.172 .91 0.050 .530.129 methanol exposure

Table 3 compares the Strehl ratios and errors (RMS (γ)) before and afterexposure to methanol of UV curable adhesive mod 137 by Chemsultants, OCA8148-2 UV curable adhesive sheet by 3M™, and acrylic based (non-UVcurable) 8172 adhesive sheet by 3M™ and the transparent sheet 32. Asillustrated by Table 3, OCA 8148-2 UV curable adhesive sheet by 3M™suitably resisted degradation due to the exposure to methanol.

FIG. 5 includes a partially exploded cross sectional view of the sensor20 and the applique 30. In the example of FIG. 5, the applique 30 alsoincludes a coating 504 on the second surface 38 of the transparent sheet32. The coating 504 may include an anti-icing coating. Examples ofanti-icing coatings include a phase separated fluorinated andhygroscopic polymer and a fluorinated and hydrophilic polymer. Thecoating 504 may additionally or alternatively include an anti-foulingcoating. Examples of anti-fouling coatings include a phase separatedfluorinated and hydrophilic polymer, a fluorinated and hydrophobicpolymer, and a fluorinated and amphiphilic polymer.

The coating 504 may additionally or alternatively include ananti-scratch coating. Examples of anti-scratch coatings include hardcoatings, such as a ceramic coating (e.g., alumina or sapphire), adiamond like carbon, a nitride (e.g., silicon nitride or aluminumnitride), and a silica-based glass.

The coating 504 may additionally or alternatively include ananti-reflective coating. Examples of anti-reflective coatings includemagnesium fluoride, calcium fluoride, sodium fluoride, porous silica, ora multi-layered interference coating including alternating layers of alow-index material (e.g., silica) and a higher index material.

The coating 504 may additionally or alternatively include a tintcoating. Examples of tint coatings include an additive that could be afilm/coating. Alternatively, the tint can be a powder incorporated intothe transparent sheet 32. The tint absorbs light to protect the sensormodule 22 and/or the clear substrate 26. For example, the tint mayabsorb visible and UV light but pass near-IR (NIR) light.

The coating 504 may additionally or alternatively include a reflectivecoating. Examples of reflective coatings include a metallic layer thatpartially or totally absorbs light or a multi-layer interference coatingthat scatters specific wavelengths of light.

The coating 504 may additionally or alternatively include a hydrophiliccoating. Examples of hydrophilic coatings include one or more layer withcharged groups, such as ammonium cations or sulfate anions. The layer(s)can be polymer layers or layers made from alkyl silanes.

The foregoing description is merely illustrative in nature and is in noway intended to limit the disclosure, its application, or uses. Thebroad teachings of the disclosure can be implemented in a variety offorms. Therefore, while this disclosure includes particular examples,the true scope of the disclosure should not be so limited since othermodifications will become apparent upon a study of the drawings, thespecification, and the following claims. It should be understood thatone or more steps within a method may be executed in different order (orconcurrently) without altering the principles of the present disclosure.Further, although each of the embodiments is described above as havingcertain features, any one or more of those features described withrespect to any embodiment of the disclosure can be implemented in and/orcombined with features of any of the other embodiments, even if thatcombination is not explicitly described. In other words, the describedembodiments are not mutually exclusive, and permutations of one or moreembodiments with one another remain within the scope of this disclosure.

Spatial and functional relationships between elements (for example,between modules, circuit elements, semiconductor layers, etc.) aredescribed using various terms, including “connected,” “engaged,”“coupled,” “adjacent,” “next to,” “on top of,” “above,” “below,” and“disposed.” Unless explicitly described as being “direct,” when arelationship between first and second elements is described in the abovedisclosure, that relationship can be a direct relationship where noother intervening elements are present between the first and secondelements, but can also be an indirect relationship where one or moreintervening elements are present (either spatially or functionally)between the first and second elements. As used herein, the phrase atleast one of A, B, and C should be construed to mean a logical (A OR BOR C), using a non-exclusive logical OR, and should not be construed tomean “at least one of A, at least one of B, and at least one of C.”

In the figures, the direction of an arrow, as indicated by thearrowhead, generally demonstrates the flow of information (such as dataor instructions) or light that is of interest to the illustration. Forexample, when element A and element B exchange a variety of informationbut information transmitted from element A to element B is relevant tothe illustration, the arrow may point from element A to element B. Thisunidirectional arrow does not imply that no other information istransmitted from element B to element A. Further, for information sentfrom element A to element B, element B may send requests for, or receiptacknowledgements of, the information to element A.

In this application, including the definitions below, the term “module”or the term “controller” may be replaced with the term “circuit.” Theterm “module” may refer to, be part of, or include: an ApplicationSpecific Integrated Circuit (ASIC); a digital, analog, or mixedanalog/digital discrete circuit; a digital, analog, or mixedanalog/digital integrated circuit; a combinational logic circuit; afield programmable gate array (FPGA); a processor circuit (shared,dedicated, or group) that executes code; a memory circuit (shared,dedicated, or group) that stores code executed by the processor circuit;other suitable hardware components that provide the describedfunctionality; or a combination of some or all of the above, such as ina system-on-chip.

The module may include one or more interface circuits. In some examples,the interface circuits may include wired or wireless interfaces that areconnected to a local area network (LAN), the Internet, a wide areanetwork (WAN), or combinations thereof. The functionality of any givenmodule of the present disclosure may be distributed among multiplemodules that are connected via interface circuits.

The term code, as used above, may include software, firmware, and/ormicrocode, and may refer to programs, routines, functions, classes, datastructures, and/or objects. The term shared processor circuitencompasses a single processor circuit that executes some or all codefrom multiple modules. The term group processor circuit encompasses aprocessor circuit that, in combination with additional processorcircuits, executes some or all code from one or more modules. Referencesto multiple processor circuits encompass multiple processor circuits ondiscrete dies, multiple processor circuits on a single die, multiplecores of a single processor circuit, multiple threads of a singleprocessor circuit, or a combination of the above. The term shared memorycircuit encompasses a single memory circuit that stores some or all codefrom multiple modules. The term group memory circuit encompasses amemory circuit that, in combination with additional memories, storessome or all code from one or more modules.

The term memory circuit is a subset of the term computer-readablemedium. The term computer-readable medium, as used herein, does notencompass transitory electrical or electromagnetic signals propagatingthrough a medium (such as on a carrier wave); the term computer-readablemedium may therefore be considered tangible and non-transitory.Non-limiting examples of a non-transitory, tangible computer-readablemedium are nonvolatile memory circuits (such as a flash memory circuit,an erasable programmable read-only memory circuit, or a mask read-onlymemory circuit), volatile memory circuits (such as a static randomaccess memory circuit or a dynamic random access memory circuit),magnetic storage media (such as an analog or digital magnetic tape or ahard disk drive), and optical storage media (such as a CD, a DVD, or aBlu-ray Disc).

What is claimed is:
 1. An applique for covering a clear substratethrough which light is at least one of transmitted and received, theapplique comprising: a transparent sheet having: a first surface; and asecond surface that is opposite the first surface; and a ultraviolet(UV) curable pressure sensitive adhesive that is disposed on the firstsurface of the transparent sheet, that is curable using UV light, andthat is configured to adhere the transparent sheet to a third surface ofthe clear substrate.
 2. The applique of claim 1 wherein the UV curablepressure sensitive adhesive includes adhesive 8148 by 3M corporation. 3.The applique of claim 2 wherein a thickness of the UV curable pressuresensitive adhesive is 2 mils.
 4. The applique of claim 1 wherein thetransparent sheet is a fluoropolymer sheet.
 5. The applique of claim 1wherein the transparent sheet is fluorinated ethylene propylene.
 6. Theapplique of claim 1 wherein the UV curable pressure sensitive adhesiveis a dry adhesive.
 7. The applique of claim 1 wherein the UV curablepressure sensitive adhesive includes a sheet of UV curable adhesive thatis cured using the UV light after application of the applique to theclear substrate.
 8. The applique of claim 1 wherein, prior toapplication of the UV curable pressure sensitive adhesive to thetransparent sheet, the first surface of the transparent sheet is treatedby at least one of an ozone treatment process, a corona treatingprocess, a chemical etching process, and a plasma treating process. 9.The applique of claim 1 wherein the UV curable pressure sensitiveadhesive is configured to adhere better to the first surface of thetransparent sheet than to the third surface of the clear substrate. 10.The applique of claim 1 wherein: the clear substrate exhibits a firstindex of refraction; the UV curable pressure sensitive adhesive exhibitsa second index of refraction after being UV cured; the transparent sheetexhibits a third index of refraction; with the third index of refractionof the transparent sheet is less than the second index of refraction;and the second index of refraction is less than the first index ofrefraction of the clear substrate.
 11. The applique of claim 1 whereinthe third surface of the clear substrate is a planar surface.
 12. Theapplique of claim 1 wherein the third surface of the clear substrate isa convex surface.
 13. The applique of claim 1 further comprising arelease liner that covers the UV curable pressure sensitive adhesive.14. The applique of claim 13 wherein the UV curable pressure sensitiveadhesive is configured to adhere better to the first surface of thetransparent sheet than to the release liner.
 15. The applique of claim 1further comprising a coating on the second surface of the transparentsheet.
 16. The applique of claim 15 wherein the coating includes atleast one of: an anti-icing coating; an anti fouling coating; ananti-scratch coating; an anti-reflective coating; a tint; a reflectivecoating; and a hydrophilic coating.
 17. A sensor comprising: a clearsubstrate having a first surface; a sensor module configured to receivelight through the clear substrate; and an applique that is adhered tothe first surface of the clear substrate and that includes: atransparent sheet having: a second surface; and a third surface that isopposite the second surface; and a ultraviolet (UV) cured pressuresensitive adhesive that is sandwiched between the second surface of thetransparent sheet and the first surface of the clear substrate and thatadheres the transparent sheet to the clear substrate.
 18. The sensor ofclaim 17 wherein the sensor module is further configured to transmitlight through the clear substrate.
 19. The sensor of claim 17 wherein:the transparent sheet is fluorinated ethylene propylene; and the UVcured pressure sensitive adhesive is adhesive 8148 by 3M corporationthat is cured using UV light.
 20. The sensor of claim 17 wherein theapplique further includes, on the third surface of the transparentsheet, at least one of: an anti-icing coating; an anti fouling coating;an anti-scratch coating; an anti-reflective coating; a tint; areflective coating; and a hydrophilic coating.